Japan’s Volcanoes

In Japan nature can be violent as well as beautiful. Here we see cherry blossoms at Flower Park Kagoshima in Ibusuki City. 924 metre-tall Kaimondake Volcano, which last erupted in 885 AD, is in the background.

We were probably all taught at school that the ground underfoot is slowly floating around on a sea of molten rock, but where I come from, this never had much relevance to everyday life. In Japan, the situation couldn’t be more different. Earthquakes and tsunami are a constant hazard, and over a hundred active volcanoes menace towns and cities throughout the country. Fortunately, volcanoes usually give out warning signs before they erupt, so it’s possible to get close up without placing yourself in dire peril. At some volcanoes you can even climb to the crater rim and look down into a lake of steaming sulphurous water, or see buildings half-buried in lava. There’s no way to get closer to our planet’s fiery interior, so I’d recommend everyone who visits Japan to go see a volcano.

Japan’s active geology is the consequence of it being at the junction of four of the Earth’s tectonic plates, all of which are constantly being pushed into one-another. The active volcanoes lie along the edges of plates, most of them in a line that stretches from subtropical Okinawa in the southwest, all the way up to the frosty island of Hokkaido in the north. A side-branch stretches south into the Pacific Ocean, in the form of a series of small islands and underwater volcanoes.

Most of Japan’s volcanoes are stratovolcanoes, meaning that as well as producing floes of lava, they also throw out rocks and ash in violent explosions. The greatest danger usually comes from streams of super hot gas and rocks that can travel at up to 700km/h, and be as hot as 1,000°C. Thankfully, Japan has a lot of experience in dealing with volcanoes (the first historical record of an eruption dates back to 553 AD), so as long as you follow official warnings you should be safe. Here are some of Japan’s most notable volcanoes, and details of how best to experience them first-hand.

Lake Okama on Mount Zao sits in a crater formed by an eruption in the 1720s. It’s also known as ‘Five Colour Lake’, because its water changes colour depending on the weather. As with many of Japan’s volcanoes, Zao is a complex volcano, meaning that it’s really a cluster of volcanoes formed by a series of eruptions. Over time Zao has acquired multiple summits, and the volcano that houses Lake Okama in its crater has it’s own name, Goshiki-dake. Mount Zao is on the border of Miyagi and Yamagata Prefectures, and is both the most active volcano in the region and a major tourist attraction.

The incredibly steep summit of Mount Io, which last erupted in 1936. Io means sulphur, which the mountain is known for ejecting in liquid form during eruptions. 1,562 metres tall, Io is on the Shiretoko Peninsula of Hokkaido, right at the far northeastern end of Japan.

An eruption in progress in April 2011 on Suwanosejima Island, which hosts one of Japan’s most active volcanoes. Despite the constant danger of eruptions, and it being a seventeen-hour ferry trip away from Kyushu, the island is home to about 50 people. (You can just make out the pier and airstrip on the right side of the island.) Suwanosejima has been populated on and off for thousands of years, with residents sometimes forced to evacuate for long periods when the volcanic activity became too intense.